<%@ page import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%@ page import="java.io.OutputStream" %>

<%!Color getRandColor(int fc, int bc) {

		Random random = new Random();
		
		if (fc > 255)
			fc = 255;
		if (bc > 255)
			bc = 255;
		
		int r = fc + random.nextInt(bc - fc);
		int g = fc + random.nextInt(bc - fc);
		int b = fc + random.nextInt(bc - fc);
		
		return new Color(r, g, b);
	}%>
<%

	try {
		
		response.setHeader("Pragma", "No-cache");
		response.setHeader("Cache-Control", "no-cache");
		response.setDateHeader("Expires", 0);
		
		int width = 80, height = 22;
		
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		OutputStream os = response.getOutputStream();
		
		Graphics g = image.getGraphics();
		Random random = new Random();
		g.setColor(getRandColor(200, 250));
		g.fillRect(0, 0, width, height);

		g.setFont(new Font("微软雅黑", Font.BOLD, 22));
		g.setColor(getRandColor(160, 200));

		// 乱线背景
		for (int i = 0; i < 35; i++) {

			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			
			g.drawLine(x, y, x + xl, y + yl);
		}

		String sRand = "";
		
		// 验证码
		for (int i = 0; i < 4; i++) {
			
			int intRand = random.nextInt(36);
			char charRand = ' ';
			
			if (intRand >= 26) {
				
				intRand = intRand + 48 - 26;
			}
			else {
				
				intRand = intRand + 65;
			}
			
			charRand = (char) intRand;
			
			String rand = String.valueOf(charRand);
			sRand += rand;
			
			g.setColor(new Color(20 + random.nextInt(110), 20 + random.nextInt(110), 20 + random.nextInt(110)));
			
			g.drawString(rand, 18 * i + 10, 20);
		}
		
		session.setAttribute("verifycode", sRand);
		g.dispose();

		ImageIO.write(image, "JPEG", os);
		
		os.flush();
		os.close();
		os = null;
		
		response.flushBuffer();
		out.clear();
		out = pageContext.pushBody();
	} catch (IllegalStateException e) {
		System.out.println(e.getMessage());
	} catch (Exception e) {
		System.out.println(e.getMessage());
	}
%>